The 25-year-old star's new album, 'Tell Me You Love Me', features two tracks, 'Ruin the Friendship' and 'Only Forever', which are about wanting more from a friendship and lyrics such as ''Put down your cigar and pick me up'' from the former track, have been seen as being about her long-time pal.

Demi said of the tracks: ''I was frustrated with a certain situation.

''And I was like, 'You know what, I'm just going to write about it.' And so I did, and sent [the songs] to that person, and that was... Interesting.

''Any time you send a song about the person, to the person--it's ballsy. It's like, 'Hey! Here's my feelings for you!' ''

And the mystery person in question had also written a song about Demi - but still nothing has happened between them.

She added in an interview with Noisey: ''They knew [about my feelings], but neither of us had acknowledged [them] before. And then it turned out that person had written a song about me, and we exchanged songs.''

''[When I sent mine] that person was like, 'That's an incredible song.' And I was like, 'Yeah, well. It's like, ''Hel-lo!'''

''They had their reasons. But, yeah.''

The lyrics and comments from Demi - who previously dated Nick's brother Joe Jonas - sparked a fan frenzy on social media.

One fan tweeted: ''demi and nick having feelings for each other is a plot twist I could've never expected f**k got and greys anatomy this is the kind of drama that has me shook in 54 languages (sic)''

Another posted: ''I always knew Nick had a huge crush on Demi.. but who knew she felt the same. I thought she hated him. I'm shook''